The present invention relates generally to a tire inflation/fill system and, more particularly, to a tire purge/fill system for controlling the build-up of tire pressure in an automobile racing environment.
Controlling the build-up of tire pressure during a racing event is always a major concern and challenge due to the fact that automobile tires heat up during a race and such heat causes the air, gas, moisture and other contaminants contained within the tire to expand and increase tire pressure. If this build-up of tire pressure is left unchecked, tire blow-outs and other tire deformation can occur. This obviously impedes the performance of the motor vehicle as well as raises safety concerns in a racing environment. In order to control this build-up of tire pressure in a racing environment, many pit crews and racing associations, such as NASCAR, use nitrogen instead of air to inflate the tires of racing vehicles. The characteristics of nitrogen as compared to air and other gases is much better for controlling the build-up of tire pressure during a racing environment since the expansion of nitrogen due to an increase in temperature is lower and better controlled as compared to air and other gases.
Evacuating all air from a tire and inflating the tire solely with nitrogen is a time consuming process. For example, one method currently used in an attempt to purge racing tires of all air prior to inflating them with nitrogen is as follows. Typically, all tires used by a particular pit crew for a particular race are lined up side-by-side. The valve stem associated with each respective tire is removed and the tire is bled of all pressurized air contained therein. Once the tires are deflated, the valve stems are replaced and the tire is filled with nitrogen. It is important to purge all air out of the tire before final inflation with nitrogen because if air is mixed with the nitrogen, air will expand at a different rate as compared to the nitrogen and the increase in tire pressure during a particular race will be greater than if all air was previously purged from the tire. The same is likewise true with respect to any moisture or other contaminants trapped within the tire. Moisture and other contaminants will likewise expand at a different expansion rate when exposed to a rise in temperature thereby further increasing the build-up of pressure in the tire during a particular racing event. In this regard, in an effort to purge the nitrogen from contaminants prior to entering the tire, a one-stage dryer or filter/absorption system is typically used to purge the nitrogen from oxygen and other contaminants prior to entry into the tire. The purer the nitrogen, the better the tire pressure can be controlled.
In an effort to substantially purge a particular tire from all air and other contaminants and to ensure that the tire is filled substantially with only nitrogen, several purging and filling sequences are typically accomplished. For example, once a tire is initially purged and filled with nitrogen, the valve stem is again removed and the nitrogen is allowed to at least partially evacuate the tire before the valve stem is again inserted and the tire is again inflated with nitrogen to a predetermined pressure. This evacuation and refilling process may occur several times in an effort to ensure that all air and other contaminants are evacuated from the tire. The tire is then filled to a predetermined pre-race pressure which is typically below racing pressure. Calculations are made as to the rate of tire pressure increase during a particular race so that the proper predetermined pre-race pressure can be established.
The purge/fill process currently used in many racing environments is time consuming and does not ensure that all air is bled from the tire since the valve stem is completely removed during each intervening evacuation and fill process.
It is therefore desirable to design and implement a tire purge/fill apparatus and system which improves the quality of the nitrogen being supplied to the tire, which is easily manipulated to both purge and fill a particular tire with nitrogen including accomplishing intervening purging and refilling operations, which is less time consuming, and which produces more consistent results with respect to all tires being filled including providing a consistent concentration or purity of nitrogen to each respective tire being filled.
Accordingly, the present invention is directed to overcoming one or more of the problems set forth above.